Old School
I am old-school. Can not help that, being the age I am. E-Mail to me is async communication, short, sweet and to the point. It is also a medium which requires sticking to a set of ground-rules or the medium becomes useless. So here are some of the rules I try very hard to stick to:
- Text only
If you want to spam people with HTML bloat just so you can add advertising to your emails, you deserve no clients and no email client.
- Interspersed commenting
Top-posting is for kindergarden (which says a lot about corporate communications). The professionals comment inline in order to keep the response close to what is being replied to. Bottom-posters: AOL called from the 90's and want their "me too!" back.
- Trim liberally
If you quote a 500 line email but you are commenting about a nit that is relevant to five lines, you need a slap around the head to catch a clue.
- Avoid responding if you are not adding anything of value to the discussion.
A "me too" post is just noise. A response that adds details and something useful (in the case of a technical issue, steps to reproduce the problem, or an environment that triggers a problem more frequently is GOLD) is what you should aim for.
The Issue
For reasons, I am subscribed to quite a few mailing lists. And mailing list hosts tends to be anal about delivering email - as they should be. It is their purpose. However, I also run my own email server, and spam is an issue. Hence spamfiltering. And my spam-filtering is apparently too good as it refuses to accept broken DKIM signed messages.
For those that do not know, there are three primary mechanisms available to provide some means of making spammers jobs harder. They are SPF, DKIM and DMARC. Simplest is DMARC - do you own the domain you claim to be posting from. DKIM signs email headers, so they can not be tampered with. SPF is more about "are you permitted to send from this domain".
So my mailserver did not want to accept emails with broken DKIM headers, correctly labelling it as spam. And for that, I was forcibly unsubscribed from two lists because my mailserver did what a good mailserver should do - reject crap. I view this a bit like victim-blaming on the mailing list server owners part, because they chose to punish the recipient, when they instead should kick the sender on the shins for posting broken shit. And before anyone start defending them that it is not their job policing those posting to their lists - a functioning email system requires dealing with that which is broken for everyones sake. Sticking the head in the sand and whining that they can not dump the shit onto others to deal with is one reason the world is in the state it is.
KAM
So, the rule-set that got me into trouble was the KAM rule-set. If you want to use it, you go to McGrail Download and grab the following files:
KAM.cf
KAM_deadweight*.cf (3 files)
KAM_heavyweight.cf
and load them as additional rule-set in your spamassassin filtering. They work really well (too well according to mailing list hosters) for getting rid of junk. And if you want to make spammers grind their teeth - REJECT what trips the filters, do not DISCARD. REJECT means the sending mail-server can not get rid of it - which SHOULD mean they actually deal with the problem rather than trying to sweep it under the rug or slopey-shoulder it onto someone else.
Mail Server
If you run one you should really try and understand how the various security mechanisms work and deploy them. The old internet adage of "be strict about what you produce and liberal with what you receive" is good to follow. So use SPF, DKIM and DMARC as they are intended - and for heavens sake, do not run a configuration where it is broken or half-ass deployed as you might as well not have it at all. If you need to test your config, make liberal use of MXToolBox as they can help you tweak and tune the setup until it passes testing. That means you know that what you send is A-grade and gives you a leg to stand on to not accept F-grade crap coming back in.
Plus, when you have your own mail server, it is interesting to just stake-out the logs and see what shenanigans actually go on out on the internet. It is a responsibility and it requires some skill and equipment, but if you want a decent solution that you might not need to tweak too much, have a look at MailCow. It is a containerised solution that has spam-filtering, sieve filters, anti-virus and much more. I am good with my simple Synology MailServer as it does what I need, but if I ever get rid of the NAS, MailCow will be where you will find me next.